Considerations on the European Standard EN 14157 Test Methods: Abrasion Resistance of Natural Stones Used for Flooring in Buildings     

Z. Karaca  N. Günes Y?lmaz  R. M. Goktan 《Rock Mechanics and Rock Engineering》2012,45(1):103-111

In Europe, the Wide Wheel abrasion (WWA) test and the B?hme abrasion (BA) test are among the most widely used standard test methods for determining abrasion resistance of natural stones, the former being the reference test method in EN 14157 Standard. However, it is stated in the Annex-A (Informative) of EN 14157 Standard that very limited data are available to provide correlations between these two test methods. To be able to fill this gap, in this study, 25 different natural stones belonging to sedimentary, metamorphic and igneous groups were tested for their abrasion resistance as well as physico-mechanical properties. Also, for a better interpretation of abrasion resistance characteristics of the tested stone materials, relationships between abrasion resistance and physico-mechanical properties were statistically examined. A statistically significant linear correlation (R ² = 0.85; P value = 0.000) was established between the WWA test and the BA test, which could be used in practice for converting the measured abrasion resistance values from one testing method to another. It was also found that the correlation between these two test methods improved significantly (R ² = 0.93; P value = 0.001) when relatively high-porosity stone materials (porosity ≥1%) were separately evaluated. Both methods of abrasion resistance employed in the present study showed statistically significant linear correlations with uniaxial compressive strength and Brazilian tensile strength, the former proving to be a more influencing parameter on resistance to abrasion. Also, from the point view of representing actual abrasion mechanism of stone materials in practice, the necessity of simulating multi-directional foot traffic in abrasion testing methods was discussed. In this respect, the reference test method in the EN 14157 Standard was criticized for not fully meeting this requirement. It was also pointed out that the reference method could have some drawbacks when applied to coarse-grained granitic rocks having cleavable minerals such as plagioclase and orthoclase feldspars.  相似文献   

Cognate clinopyroxene from Paleogene mantle xenolith-bearing basanite lavas (East Serbia, SE Europe): the role of dissolution of mantle orthopyroxene     

Vladica Cvetkovi?  Suzana Eri?  Ma?a Radivojevi?  Kristina ?ari? 《Mineralogy and Petrology》2012,106(3-4):131-150

The study focuses on clinopyroxene from mantle xenolith-bearing East Serbian basanites and suggests that dissolution of mantle orthopyroxene played an important role in at least some stages of the crystallization of these alkaline magmas. Five compositional types of clinopyroxene are distinguished, some of them having different textural forms: megacrysts (Type-A), green/colourless-cored phenocrysts (Type-B), overgrowths and sieve-textured cores (Type-C), rims and matrix clinopyroxene (Type-D), and clinopyroxene from the reaction rims around orthopyroxene xenocrysts (Type-E). Type-A is high-Al diopside that probably crystallized at near-liquidus conditions either directly from the host basanite or from compositionally similar magmas in previous magmatic episodes. Type-B cores show high ^VIAl/^IVAl≥1 and low Mg# of mostly <75 and are interpreted as typical xenocrysts. Type-C, D and E are interpreted as typical cognate clinopyroxene. Type-D has Mg#<78, Al₂O₃?=?6–13?wt.%, TiO₂?=?1.5–4.5?wt.%, and Na₂O?=?0.4–0.8?wt.% and compositionally similar clinopyroxene is calculated by MELTS as a phase in equilibrium with the last 30?% of melt starting from the average host lava composition. Type-C has Mg#?=?72–89, Al₂O₃?=?4.5–9.5?wt.%, TiO₂?=?1–2.5?wt.%, Na₂O?=?0.35–1?wt.% and Cr₂O₃?=?0.1–1.5?wt.%. This clinopyroxene has some compositional similarities to Type-E occurring exclusively around mantle orthopyroxene. Cr/Al vs Al/Ti and Cr/Al vs Na/Ti plots revealed that Type-C clinopyroxene can crystallize from a mixture of the host basanite magma and 2–20?wt.% mantle orthopyroxene. Sieve-textured Type-C crystals show characteristics of experimentally produced skeletal clinopyroxene formed by orthopyroxene dissolution suggesting that crystallization of Type-C was both texturally and compositionally controlled by orthopyroxene breakdown. According to FeO/MgO^cpx/melt modelling the first clinopyroxene precipitating from the host basanite was Type-A (T?~?1250?°C, p?~?1.5?GPa). Dissolution of orthopyroxene produced decreasing FeO/MgO^melt and crystallization of Type-E and sieve-textured Type-C clinopyroxene (0.3–0.8?GPa and 1200–1050?°C). The melt composition gradually shifted towards higher FeO/MgO^melt ratios precipitating more evolved Type-C and Type-D approaching near-solidus conditions (<0.3?GPa; ~950?°C).  相似文献   

A Raman spectroscopic study on the structural disorder of monazite–(Ce)     

Katja Ruschel  Lutz Nasdala  Andreas Kronz  John M. Hanchar  Daniel M. T?bbens  Radek ?koda  Friedrich Finger  Andreas M?ller 《Mineralogy and Petrology》2012,105(1-2):41-55

This study addresses whether Raman spectra can be used to estimate the degree of accumulated radiation damage in monazite-(Ce) samples whose chemical composition was previously determined. Our results indicate that the degree of disorder in monazite–(Ce), as observed from increasing Raman band broadening, generally depends on both the structural state (i.e., radiation damage) and the chemical composition (i.e., incorporation of non-formula elements). The chemical effects were studied on synthetic orthophosphates grown using the Li-Mo flux method, and non radiation-damaged analogues of the naturally radiation-damaged monazite–(Ce) samples, produced by dry annealing. We found that the “chemical” Raman-band broadening of natural monazite–(Ce) can be predicted by the empirical formula, $$ {\hbox{FWHM}} {\hbox{[c}}{{\hbox{m}}^{ - {1}}}{]} = {3}{.95} + {26}{.66} \times {\hbox{(Th}} + {\hbox{U}} + {\hbox{Ca}} + {\hbox{Pb)}} {\hbox{[apfu]}} $$ where, FWHM = full width at half maximum of the main Raman band of monazite–(Ce) (i.e., the symmetric PO₄ stretching near 970?cm^?1), and (Th+U+Ca+Pb) = sum of the four elements in apfu (atoms per formula unit). Provided the chemical composition of a natural monazite–(Ce) is known, this “chemical band broadening” can be used to estimate the degree of structural radiation damage from the observed FWHM of the ν₁(PO₄) band of that particular sample using Raman spectroscopy. Our annealing studies on a wide range of monazite–(Ce) reference materials and other monazite–(Ce) samples confirmed that this mineral virtually never becomes highly radiation damaged. Potential advantages and the practical use of the proposed method in the Earth sciences are discussed.  相似文献   

Risk evaluation of China’s natural disaster systems: an approach based on triangular fuzzy numbers and stochastic simulation   总被引：6，自引：6，他引：0  

Ju-Liang?Jin  Yi-Ming?WeiEmail author  Le-Le?Zou  Li?Liu  Juan?Fu 《Natural Hazards》2012,62(1):129-139

To deal effectively with the evaluation problem of natural disaster risk system affected by many uncertain factors, a multivariate connection number expression is presented. This expression is based on the index samples and evaluation grade criterions of natural disaster risk system and is capable of describing the hierarchy property and fuzziness of membership relationship between index samples and evaluation grade criterions. In this proposed method, the fuzzy evaluation grade criterion problem is resolved by combining triangular fuzzy numbers with multivariate connection number theory, and triangular fuzzy numbers are used to express the discrepancy degree coefficients of connection number and evaluation index weights. Accordingly, a connection number-based evaluation method for the natural disaster system of China (named CN-TFN for short) is established using triangular fuzzy numbers and stochastic simulation. The application results show that the spatial distribution of natural disaster risk grades of China has the trend of aggrandizement from west to east of China. The economically developed and densely populated coastal areas are very likely to have a high level of natural disaster risk grade or above; thus, these areas are the key regions of the natural disaster risk management of China. The results also show that the CN-TFN is able to reflect practical conditions of the evaluation problem of natural disaster system and to provide more reliability information as compared to the existing evaluation methods. This is as a result of its comprehensive usage of various information of subjective and objective uncertainties in the evaluation process of natural disaster risk system and its expression by confidence intervals. Due to the simplicity and generalization, the CN-TFM is applicable to comprehensive risk grade evaluation of various natural disaster systems.  相似文献   

Structure and nuclear density distribution in the cheralite—CaTh(PO4)2: studies of its behaviour under high pressure (36?GPa)     

Philippe E. Raison  Stephen Heathman  Gilles Wallez  Carmen E. Zvoriste  Denis Bykov  Ga?l Ménard  Emmanuelle Suard  Karin Popa  Nicolas Dacheux  Rudy J. M. Konings  Roberto Caciuffo 《Physics and Chemistry of Minerals》2012,39(8):685-692

The crystal structure of the cheralite—CaTh(PO₄)₂—has been revisited by neutron diffraction and its behaviour under high pressure investigated by X-ray diffraction up to 36?GPa. The neutron diffraction data at ambient pressure gave a more accurate determination of the Ca/Th cation position than previous XRD data, taking advantage that the neutron scattering lengths of calcium and thorium are of same order of magnitude. The nuclear density distribution was also determined using the maximum entropy method (MEM) confirming that the two cations are not located at the same position in the unit cell but are slightly displaced from one another along a specific direction in order to minimize the electrostatic repulsion with the surrounding phosphorus atoms. At high pressure, the compound did not show any phase transition or amorphization. From the evolution of the unit-cell volume as a function of the pressure, the zero-pressure bulk modulus B₀ and its pressure derivative B₀ ^′ have been determined by fitting the experimental compressibility curve to the Birch–Murnaghan equation of state. The results are B₀?=?140(2) GPa and B ₀ ^′ ?=?4.4(4) GPa.  相似文献   

Detection of smectites in ppm and sub-ppm concentrations using dye molecule sensors     

Marcel?Lofaj  Juraj?BujdákEmail author 《Physics and Chemistry of Minerals》2012,39(3):227-237

Methylene blue and rhodamine 6G were used as molecular sensors for the spectrophotometric titrations of the aqueous colloids of clay minerals (montmorillonite, illite and kaolinite). The dyes adsorbed on colloid particles form molecular aggregates, which exhibit spectral properties significantly different from those of dye solutions. Spectrophotometric titrations provide the most sensitive detection of smectites in aqueous colloids (sub-ppm concentrations); and the sensitivity further increases using second derivative spectroscopy. The endpoint of spectrophotometric titrations can be used for the determination of exchange capacity of the mineral in colloids and in this way to estimate its amount. The method is selective only to expandable clays, which was proven by experiments with kaolinite and illite. Spectrophotometric titrations have promising future in the analysis of clays and can be applied in many fields of geology, mineralogy, chemistry, material sciences or in industry. Its application may expand to the analysis of other nanomaterials built from charged particles and exhibiting metachromasy in the systems with organic dyes.  相似文献   

Vulnerability assessment in natural hazard and risk analysis: current approaches and future challenges   总被引：10，自引：9，他引：1  

Sven Fuchs  J?rn Birkmann  Thomas Glade 《Natural Hazards》2012,64(3):1969-1975

  相似文献   

The effect of chemical composition and oxygen fugacity on the electrical conductivity of dry and hydrous garnet at high temperatures and pressures   总被引：3，自引：0，他引：3  

Lidong?Dai  Heping?LiEmail author  Haiying?Hu  Shuangming?Shan  Jianjun?Jiang  Keshi?Hui 《Contributions to Mineralogy and Petrology》2012,163(4):689-700

The in situ electrical conductivity of hydrous garnet samples (Py₂₀Alm₇₆Grs₄–Py₇₃Alm₁₄Grs₁₃) was determined at pressures of 1.0–4.0 GPa and temperatures of 873–1273 K in the YJ-3000t apparatus using a Solartron-1260 impedance/gain-phase analyzer for various chemical compositions and oxygen fugacities. The oxygen fugacity was controlled by five solid-state oxygen buffers (Fe₂O₃ + Fe₃O₄, Ni + NiO, Fe + Fe₃O₄, Fe + FeO, and Mo + MoO₂). Experimental results indicate that within a frequency range from 10⁻² to 10⁶ Hz, electrical conductivity is strongly dependent on signal frequency. Electrical conductivity shows an Arrhenius increase with temperature. At 2.0 GPa, the electrical conductivity of anhydrous garnet single crystals with various chemical compositions (Py₂₀Alm₇₆Grs₄, Py₃₀Alm₆₇Grs₃, Py₅₆Alm₄₃Grs₁, and Py₇₃Alm₁₄Grs₁₃) decreases with increasing pyrope component (Py). With increasing oxygen fugacity, the electrical conductivity of dry Py₇₃Alm₁₄Grs₁₃ garnet single crystal shows an increase, whereas that of a hydrous sample with 465 ppm water shows a decrease, both following a power law (exponents of 0.061 and −0.071, respectively). With increasing pressure, the electrical conductivity of this hydrous garnet increases, along with the pre-exponential factors, and the activation energy and activation volume of hydrous samples are 0.7731 ± 0.0041 eV and −1.4 ± 0.15 cm³/mol, respectively. The results show that small hopping polarons ( \textFe_\textMg ^· ) \left( {{\text{Fe}}_{\text{Mg}}^{ \cdot } } \right) and protons ( \textH ^· {\text{H}}^{ \cdot } ) are the dominant conduction mechanisms for dry and wet garnet single crystals, respectively. Based on these results and the effective medium theory, we established the electrical conductivity of an eclogite model with different mineral contents at high temperatures and high pressures, thereby providing constraints on the inversion of field magnetotelluric sounding results in future studies.  相似文献   

Magma plumbing beneath Anak Krakatau volcano, Indonesia: evidence for multiple magma storage regions     

B?rje Dahren  Valentin R. Troll  Ulf B. Andersson  Jane P. Chadwick  Màiri F. Gardner  Kairly Jaxybulatov  Ivan Koulakov 《Contributions to Mineralogy and Petrology》2012,163(4):631-651

Understanding magma plumbing is essential for predicting the behaviour of explosive volcanoes. We investigate magma plumbing at the highly active Anak Krakatau volcano (Indonesia), situated on the rim of the 1883 Krakatau caldera by employing a suite of thermobarometric models. These include clinopyroxene-melt thermobarometry, plagioclase-melt thermobarometry, clinopyroxene composition barometry and olivine-melt thermometry. Petrological studies have previously identified shallow magma storage in the region of 2–8 km beneath Krakatau, while existing seismic evidence points towards mid- to deep-crustal storage zone(s), at 9 and 22 km, respectively. Our results show that clinopyroxene in Anak Krakatau lavas crystallized at a depth of 7–12 km, while plagioclase records both shallow crustal (3–7 km) and sub-Moho (23–28 km) levels of crystallization. These magma storage regions coincide with well-constrained major lithological boundaries in the crust, implying that magma ascent and storage at Anak Krakatau is strongly controlled by crustal properties. A tandem seismic tomography survey independently identified a separate upper crustal (<7 km) and a lower to mid-crustal magma storage region (>7 km). Both petrological and seismic methods are sensitive in detecting magma bodies in the crust, but suffer from various limitations. Combined geophysical and petrological surveys, in turn, offer increased potential for a comprehensive characterization of magma plumbing at active volcanic complexes.  相似文献   

Calcic amphiboles in calc-alkaline and alkaline magmas: thermobarometric and chemometric empirical equations valid up to 1,130°C and 2.2 GPa     

Filippo?RidolfiEmail author  Alberto?Renzulli 《Contributions to Mineralogy and Petrology》2012,163(5):877-895

The following article presents constraints of the stability of Mg-rich (Mg/(Mg + Fe²⁺) > 0.5) calcic amphibole in both calc-alkaline and alkaline magmas, testing of previous thermobarometers, and formulation of new empirical equations that take into consideration a large amount of literature data (e.g. more than one thousand amphibole compositions among experimental and natural crystals). Particular care has been taken in choosing a large number of natural amphiboles and selecting quality experimental data from literature. The final database of experimental data, composed of 61 amphiboles synthesized in the ranges of 800–1,130°C and 130–2,200 MPa, indicates that amphibole crystallization occurs in a horn-like P–T stability field limited by two increasing curves (i.e. the thermal stability and an upper limit), which should start to bend back to higher pressures. Among calcic amphiboles, magnesiohornblendes and tschermakitic pargasites are only found in equilibrium with calc-alkaline melts and crystallize at relatively shallow conditions (P up to ~1 GPa). Kaersutite and pargasite are species almost exclusively found in alkaline igneous products, while magnesiohastingsite is equally distributed in calc-alkaline and alkaline rocks. The reliability of previous amphibole applications was checked using the selected experimental database. The results of this testing indicate that none of the previous thermobarometers can be successfully used to estimate the P, T and fO₂ in a wide range of amphibole crystallization conditions. Multivariate least-square analyses of experimental amphibole compositions and physico-chemical parameters allowed us to achieve a new thermobarometric model that gives reasonably low uncertainties (T ± 23.5°C, P ± 11.5%, H₂O_melt ± 0.78wt%) for calc-alkaline and alkaline magmas in a wide range of P–T conditions (up to 1,130°C and 2,200 MPa) and ∆NNO values (±0.37 log units) up to 500 MPa. The ^AK-^[4]Al relation in amphibole can be readily used to distinguish crystals of calc-alkaline liquids from those of alkaline magmas. In addition, several chemometric equations allowing to estimate the anhydrous composition of the melts in equilibrium with amphiboles of calc-alkaline magmas were derived.  相似文献